The present invention relates to a full-concealed wiper driving system for a vehicle and, more particularly, to a wiper driving system for readily switching a switching mechanism for switching a lower returning position of a wiper blade.
In a full-concealed wiper in which wiper arms and a wiper blade are contained under a hood, the wiper arms and the wiper blades are slightly raised from the storage position under the hood to set the position exposed on the hood as the lower returning position, and reciprocatedly wipe a windshield glass between the lower returning position and an upper returning position as ordinarily.
To execute this operation, a height moving down mechanism for moving the wiper arms and the wiper blades from the lower returing position to the storage position is required in additiqn to a mechanism for ordinarily wiping the wiper arms and the wiper blades.
Various type of height moving down mechanisms are heretofore known, but all are complicated in structure and expensive.
Thus, a full-concealed wiper which does not use the height moving down mechanism has been developed. This wiper uses the storage position as a lower returning position to move the wiper arms and the wiper blades to the storage position even in the ordinary wiping operation (Disclosed on pages 6-33 to 38 in the Instruction Manual of Toyota Crown new model issued on Aug. 31, 1983, Japan).
However, when the storage positions of the wiper arms and the wiper blades are thus set at the lower returning positions, there arises a problem that the wiper arms and the wiper blades cannot move to the storage position of the lower returning position when snow stores near the storage position at snow falling time, thereby causing the wipers to be locked.
Therefore, in the full-concealed wiper in which the storage positions are used as the lower returning position, a switching mechanism for switching the position slightly raised from the storage position to the lower returning position at snow falling time is provided to eliminate the locking state of the wipers at the snow falling time.
This switching mechanism is constructed as below.
FIGS. 4(A) and 4(B) show the structure of a coupling section of a crank arm 1 to a link 2 and its operating state. An eccentric bush 3 is provided at the coupling section of the crank arm 1 to the link 2. The eccentric bush 3 is formed substantially in a cylindrical shape to be coupled relatively rotatably with the end of the link 2 on the circumferential surface, and a pin 4 projected at the end of the crank arm 1 is penetrated at the position displaced from the axial center of the cylindrical shape. The pin 4 and the eccentric bush 3 are relatively rotatably coupled with each other. A slider 5 is slidably held at the eccentric bush 3, the slidable end of the slider 5 is selectively engaged with a cutout 42 at the end of the crank arm 1 or a guide 6 at the end of the link 2 to arbitrarily secure the eccentric bush 3 to the crank arm 1 side or the link 2 side.
Thus, as shown in FIG. 4(A), when the slider 5 is engaged with the cutout of the crank arm 1 to fix the eccentric bush 3 to the crank arm 1 side, the eccentric bush 3 relatively rotates to the link 2, but does not relatively rotate to the crank arm 1. Thus, when the output shaft 7 of the wiper motor rotates the crank arm 1 at radius R, the eccentric bush 3 rotates as shown in FIG. 5(A).
When the slider 5 is, on the other hand, engaged with the guide 6 of the link 2 as shown in FIG. 4(B) to secure the bush 3 to the link 2 side, the bush 3 relatively rotates to the crank arm 1, but does not relatively rotate to the link 2. Thus, when the output shaft 7 of the wiper motor rotates the crank arm 1 at a radius R, the bush 3 rotates as shown in FIG. 5(B).
As apparent from the comparison of FIGS. 4(A) and 4(B) with FIGS. 5(A), 5(B), the positions of the bush 3 when the wiper blade is returned at the upper returning position are the same in both FIGS. 5(A) and 5(B), but the positions of the bush 3 when the wiper blade is returned at the lower returning psition are separated at a shorter distance from the output shaft 7 in FIG. 5(B) as compared with that of FIG. 5(A).
As a result, when the slider 5 is engaged with the cutout 42 of the crank arm 1 as shown in FIG. 4(A), the wiper blade 8 is moved to the vicinity of the lowermost end of the windshield 9 as shown in FIGS. 6(A), 7(A) and by 8a in FIG. 8, and the lower returning position of the wiper blade 8 becomes its storage position. In other words, the wiper arm 10 and the wiper blade 8 are stored under the hood 11 at the lower.returning position.
On the other hand, when the slider 5 is engaged with the guide 6 of the link 2 as shown in FIG. 4(B), the wiper blade 8 is moved only to the upper side of the storage position, and the lower returning position of the wiper blade 8 is as shown in FIGS. 6(B) and 7(B) and by 8b in FIG. 8.
However, since this switching mechanism is provided in the coupling section of the crank arm 1 with the link 2, the mechanism is generally disposed in a cowl space inside a compartment from an engine room, it is difficult to switch the slider 5. Thus, as shown in FIG. 9, a small opening 13 is formed at a cowl outer panel 12, a driver 14 is inserted from the opening 13 as shown in FIGS. 10(A), 10(B), 11(A), 11(B) and to switch the slider 5. FIG. 10(A) shows that the sliding end of the slider 5 is engaged with the cutout of the end of the crank arm 1 by the driver 14 FIG. 10(B) that the slider is engaged with the guide 6 of the link 2. FIG. 11(A) shows that the sliding end of the slider 5 is engaged with the guide 6 of the link 2 by the driver 14 FIG. 11(B) that the slider is engaged with the cutout of the end of the crank arm 1. In FIG. 9, reference numeral 19 designates a grommet for ordinarily closing the opening 13.
In addition, since this switching operation moves the slider 5 between the cutout of the end of the crank arm 1 and the guide 6 of the end of the link 2 as described above, this operation can be performed only in the state that both ends are opposed. In other words, the wiper must be operated to be switched by disposing the wiper blade 8 at the upper returning position in a complicated manner.